From 60cf3ab0d8cb7f519d16489d272fdf6e496b643f Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sat, 5 Oct 1991 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1991-10-05

---
 pc/devfloppy.c |  2 +-
 pc/mmu.c       | 13 +++++++++++--
 pc/trap.c      |  8 ++++++--
 port/proc.c    | 41 +++++++++++++++++++++--------------------
 port/segment.c |  1 -
 5 files changed, 39 insertions(+), 26 deletions(-)

diff --git a/pc/devfloppy.c b/pc/devfloppy.c
index 2bc9dc37b3add9ad02668e261810310282db235c..6809c2c30f86ec71af1bd7de9385881ac4f23fa5 100644
--- a/pc/devfloppy.c
+++ b/pc/devfloppy.c
@@ -633,7 +633,7 @@ floppysense(void)
 	if(floppycmd() < 0)
 		return -1;
 	if(floppyresult() < 2){
-print("can't read sense response\n");
+/*print("can't read sense response\n");/**/
 		fl.confused = 1;
 		return -1;
 	}
diff --git a/pc/mmu.c b/pc/mmu.c
index 3f5bfe92c431455afb4967d0a0c95600f28ce126..33aef5a5956bca020d78a2c389bd3cfe18ea1d0d 100644
--- a/pc/mmu.c
+++ b/pc/mmu.c
@@ -297,6 +297,7 @@ putmmu(ulong va, ulong pa, Page *pg)
 	ulong *pt;
 	Proc *p;
 	char err[64];
+	int x;
 
 	if(u==0)
 		panic("putmmu");
@@ -313,8 +314,16 @@ putmmu(ulong va, ulong pa, Page *pg)
 	 *  into it.
 	 */
 	if(p->mmutop == 0){
-		p->mmutop = mmugetpage(0);
-		memmove((void*)p->mmutop->va, (void*)ktoppg.va, BY2PG);
+		/*
+		 *  N.B. The assignment to pg is neccessary.
+		 *  We can't assign to p->mmutop until after
+		 *  copying ktoppg into the new page since we might
+		 *  get scheded in this code and p->mmutop will be
+		 *  pointing to a bad map.
+		 */
+		pg = mmugetpage(0);
+		memmove((void*)pg->va, (void*)ktoppg.va, BY2PG);
+		p->mmutop = pg;
 	}
 	top = (ulong*)p->mmutop->va;
 
diff --git a/pc/trap.c b/pc/trap.c
index d0db2096aa93bd592f4672f665ade225d341d1ff..d9f75d4dfd7b578d6f57da9657723551678d9273 100644
--- a/pc/trap.c
+++ b/pc/trap.c
@@ -173,11 +173,15 @@ trap(Ureg *ur)
 {
 	int v;
 	int c;
+	static int spuriousfloppy;
 
 	v = ur->trap;
 	if(v>=256 || ivec[v] == 0){
-		panic("bad trap type %d %lux %lux %lux\n", v, ur->pc, int0mask, int1mask);
-		return;
+		if(v == 10 && spuriousfloppy == 0){
+			v = Floppyvec;
+			spuriousfloppy = 1;
+		}else
+			panic("bad trap type %d %lux %lux %lux\n", v, ur->pc, int0mask, int1mask);
 	}
 
 	/*
diff --git a/port/proc.c b/port/proc.c
index 5089e28b01a0fed757abb5c4facbc7f0ff06cf2d..af62434879631063a065d9e9c19e20b9a11d56ee 100644
--- a/port/proc.c
+++ b/port/proc.c
@@ -534,26 +534,27 @@ pexit(char *exitstr, int freemem)
 	else
 		wq->w.msg[0] = '\0';
 
-	/* Find my parent */
-	p = c->parent;
-
-	lock(&p->exl);
-	/* My parent still alive */
-	if(p->pid == c->parentpid && p->state != Broken && p->nwait < 128) {	
-		p->nchild--;
-		p->time[TCUser] += c->time[TUser] + c->time[TCUser];
-		p->time[TCSys] += c->time[TSys] + c->time[TCSys];
-
-		wq->next = p->waitq;
-		p->waitq = wq;
-		p->nwait++;
-		unlock(&p->exl);
-
-		wakeup(&p->waitr);
-	}
-	else {
-		unlock(&p->exl);
-		freewaitq(wq);
+	if(c->kp == 0) {
+		/* Find my parent */
+		p = c->parent;
+		lock(&p->exl);
+		/* My parent still alive */
+		if(p->pid == c->parentpid && p->state != Broken && p->nwait < 128) {	
+			p->nchild--;
+			p->time[TCUser] += c->time[TUser] + c->time[TCUser];
+			p->time[TCSys] += c->time[TSys] + c->time[TCSys];
+	
+			wq->next = p->waitq;
+			p->waitq = wq;
+			p->nwait++;
+			unlock(&p->exl);
+	
+			wakeup(&p->waitr);
+		}
+		else {
+			unlock(&p->exl);
+			freewaitq(wq);
+		}
 	}
 
 	if(!freemem)
diff --git a/port/segment.c b/port/segment.c
index 1b1571b62aac143373166ed5e5ae522c309c54c5..7ab3e89708ef2894df66271cafb7a1fb0876420b 100644
--- a/port/segment.c
+++ b/port/segment.c
@@ -346,7 +346,6 @@ ibrk(ulong addr, int seg)
 	newtop = PGROUND(addr);
 	newsize = (newtop-s->base)/BY2PG;
 	if(newtop < s->top) {
-		print("down brk\n");
 		mfreeseg(s, newtop, (s->top-newtop)/BY2PG);
 		qunlock(&s->lk);
 		return 0;